Media files, for example in the form of video streams provided from video servers, are requested by clients over the internet in increasing numbers. In many cases, capabilities of the client's terminal or bandwidth limitations, may make it necessary or advantageous to process the original media file received from the video server, by adapting it.
FIG. 1 illustrates a general media delivery system 100 of the prior art, including one or more media source nodes 102, a number of media client nodes 104.1 to 104.N, and a media adaptation server 106. A network 108, typically the Internet, provides connectivity between the media source nodes 102 and the media adaptation server 106, as well as between the media adaptation server 106 and the media client nodes 104.
The media adaptation server 106 includes an adaptation engine 110 for processing original media files received from the media source node 102 as required, into adapted versions of the respective media files, before forwarding the adapted versions to the requesting media client node 104. In some cases, the original media file may be forwarded unprocessed to a media client node 104. The individual type of media adaptation for each media client node 104 depends on characteristics of the receiving node, which may be stored in a terminal profile database 112 of the media adaptation server 106. Media adaptation may include various processing functions such as transcoding, coding format conversion, trans-rating, trans-sizing, encryption and compression, to mention just a few.
The media adaptation server 106 may further include a media cache 114, for caching requested media files as well as adapted media files. A major purpose of caching media files, including adapted media files, is to avoid having to repeatedly download the original media file from the media source node 102 and re-adapting it.
However, existing systems have not fully provided the caching of media files in a way to utilize the cache capacity more effectively.
Accordingly, a method and system to improve the efficiency and utility of caching media files, including adapted media files, is required.